class_docstr: For testing of basic composite element types
code: def setUp(self):
      self.data1 = np.zeros((10, 2))
      self.data2 = np.ones((10, 2))
      self.data3 = np.ones((10, 2)) * 2
  
      self.view1 = Element(self.data1, label="view1")
      self.view2 = Element(self.data2, label="view2")
      self.view3 = Element(self.data3, label="view3")
  
file_path: holoviews/holoviews/tests/core/test_layers.py
imports: import unittest
  import numpy
  from holoviews import Element, NdOverlay
label_desc: Use image node_id 1 for calling the CompositeTest obj's underlying member method code with example usage: obj.setUp() without return types